CN114114108A - Low-cost modular liquid nitrogen low-temperature multi-core magnetic resonance probe - Google Patents
Low-cost modular liquid nitrogen low-temperature multi-core magnetic resonance probe Download PDFInfo
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- CN114114108A CN114114108A CN202111319366.1A CN202111319366A CN114114108A CN 114114108 A CN114114108 A CN 114114108A CN 202111319366 A CN202111319366 A CN 202111319366A CN 114114108 A CN114114108 A CN 114114108A
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- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 106
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- 229910000503 Na-aluminosilicate Inorganic materials 0.000 claims description 4
- 239000000919 ceramic Substances 0.000 claims description 4
- 235000012217 sodium aluminium silicate Nutrition 0.000 claims description 4
- 239000000429 sodium aluminium silicate Substances 0.000 claims description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 3
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K13/00—Thermometers specially adapted for specific purposes
- G01K13/006—Thermometers specially adapted for specific purposes for cryogenic purposes
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/34—Constructional details, e.g. resonators, specially adapted to MR
- G01R33/34015—Temperature-controlled RF coils
- G01R33/3403—Means for cooling of the RF coils, e.g. a refrigerator or a cooling vessel specially adapted for housing an RF coil
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
- G01K1/02—Means for indicating or recording specially adapted for thermometers
- G01K1/026—Means for indicating or recording specially adapted for thermometers arrangements for monitoring a plurality of temperatures, e.g. by multiplexing
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- G—PHYSICS
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- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/02—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using thermoelectric elements, e.g. thermocouples
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/34—Constructional details, e.g. resonators, specially adapted to MR
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/34—Constructional details, e.g. resonators, specially adapted to MR
- G01R33/34092—RF coils specially adapted for NMR spectrometers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver
- G01R33/3621—NMR receivers or demodulators, e.g. preamplifiers, means for frequency modulation of the MR signal using a digital down converter, means for analog to digital conversion [ADC] or for filtering or processing of the MR signal such as bandpass filtering, resampling, decimation or interpolation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver
- G01R33/3628—Tuning/matching of the transmit/receive coil
- G01R33/3635—Multi-frequency operation
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- Condensed Matter Physics & Semiconductors (AREA)
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- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
The invention discloses a low-cost modularized liquid nitrogen low-temperature multi-core magnetic resonance probe, which comprises a Dewar, a pluggable coil and a front-end gain amplifier, wherein the Dewar comprises a cylindrical interlayer cavity, the center of the cylindrical interlayer cavity forms a room-temperature cavity, the interlayer of the cylindrical interlayer cavity is divided into a vacuum cavity and a liquid nitrogen cavity by a liquid nitrogen container wall, the vacuum cavity is positioned between the room-temperature cavity and the liquid nitrogen cavity, the pluggable coil and the front-end gain amplifier are arranged in the vacuum cavity, the pluggable coil comprises a coil part and a pluggable base, the coil part is connected with the pluggable base, and the pluggable coil is connected with the front-end gain amplifier. The invention can realize the emission of radio frequency pulse and the receiving of magnetic resonance signals, and can be suitable for the whole body imaging of small animals; low design cost and low running cost can be realized; the signal-to-noise ratio of the magnetic resonance signal can be effectively improved.
Description
Technical Field
The invention relates to the technical field of nuclear magnetic resonance instruments, in particular to a low-cost modularized liquid nitrogen low-temperature multi-nuclear magnetic resonance probe which is suitable for a nuclear magnetic resonance imager or a nuclear magnetic resonance spectrometer and is used for exciting and collecting magnetic resonance signals of different types of atomic nuclei in a liquid nitrogen low-temperature state.
Background
The nuclear magnetic resonance probe device is an indispensable component of a nuclear magnetic resonance instrument and is used for realizing functions of transmitting, receiving and the like of radio frequency pulses. With the continuous expansion of the research field of nuclear magnetic resonance technology, nuclear magnetic resonance instrument systems increasingly develop towards the direction of multi-core collection and rapid collection, and these new requirements put forward higher requirements on probes of nuclear magnetic resonance instruments, on one hand, the collection speed is required to be increased, the experimental efficiency is improved, on the other hand, the signal-to-noise ratio is required to be improved, and therefore, the imaging quality is improved.
In conventional magnetic resonance imaging experiments, as the physical size of the imaging subject decreases or the detection frequency decreases, the noise contribution usually dominates, mainly manifested as the thermal noise in the coil and the device conductors has a greater and greater influence on the signal-to-noise ratio. The signal-to-noise ratio increases as the temperature of the coil (including the preamplifier) decreases.
Bruker corporation of commercial magnetic resonance equipment currently proposes a solution for cryocoils for small animal imaging, this solution cools the coil to 30K by a helium closed loop system, which requires a refrigerator to be connected to the coil and close to the magnetic resonance scanner, and also requires a strong heat source at the animal site, resulting in a very high thermal gradient (>220 ℃) from coil to sample distance, experimental results show that the signal-to-noise gain on the room temperature coil is highly dependent on the sample and the resonance frequency, with reported 2.0-2.2 fold increase in signal-to-noise ratio for the mouse brain at 200MHz, 2.4-2.5 fold increase in brain for the mouse at 400MHz, 3.0-4.0 fold increase in heart for the mouse at 400MHz, 3.0-3.5 fold increase in brain for the mouse at 100MHz, these test results strongly indicate the great potential of cryoprobes in improving signal-to-noise ratio.
However, this solution requires extremely high economic costs, making it difficult to make it more widely applicable. For small coils for animal magnetic resonance imaging, the use of some liquid nitrogen as a coolant rather than a dedicated liquid helium cryogen is a better option because the economic cost of liquid nitrogen is relatively low. The document reports that Elabyad et al immerse the coil directly in liquid nitrogen and place a solid insulating layer around the coil, resulting in a 2.7 times signal-to-noise gain (resonance frequency 18.68MHz) of the rat heart, Hu et al propose a more complex method of insulating with a vacuum chamber, which results in a signal-to-noise gain of 1.6 times in the mouse brain under a 3T magnetic field, but in this case it is necessary to keep vacuum pumping during the experiment to maintain the insulation, and poinier-Quinot et al propose an autoclavet with a thermostating time of 5 hours for cooling the superconducting coil, but the practical benefit of the cryocoil is limited for in vivo imaging of larger objects due to the increased distance of the superconducting coil to the sample and the possible deterioration of the cryostats.
In conclusion, the signal-to-noise ratio can be improved by 2-4 times by reducing the temperature of the probe (including the coil, the preamplifier and the like). However, for wider applications, it is required to reduce the cost as much as possible while ensuring the signal-to-noise ratio gain, and to achieve both the robustness and flexibility of the probe. However, no relevant literature reports exist at present for a low-cost low-temperature magnetic resonance probe which simultaneously meets the design requirements, belongs to the technical blank field, and is a key problem to be solved urgently in the technical field of nuclear magnetic resonance instruments.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the low-cost modularized liquid nitrogen low-temperature multi-core magnetic resonance probe, which is designed in a modularized mode so that a coil and a preamplifier can be replaced under the imaging experiments of different atomic nuclei, and has the potential of expanding to clinical application.
The above object of the present invention is achieved by the following technical solutions:
a low-cost modularized liquid nitrogen low-temperature multi-core magnetic resonance probe comprises a Dewar, a pluggable coil and a front-end gain amplifier, wherein the Dewar comprises a cylindrical interlayer cavity, the center of the cylindrical interlayer cavity forms a room-temperature cavity, the interlayer of the cylindrical interlayer cavity is divided into a vacuum cavity and a liquid nitrogen cavity by a liquid nitrogen container wall, the vacuum cavity is positioned between the room-temperature cavity and the liquid nitrogen cavity,
the pluggable coil and the front-end gain amplifier are arranged in the vacuum cavity, the pluggable coil comprises a coil part and a pluggable base, the coil part and the pluggable base are connected in a pluggable mode, and the pluggable coil is connected with the front-end gain amplifier.
The pluggable base and the front-end gain amplifier of the coil are connected with the wall of the liquid nitrogen container through low-temperature glue.
The vacuum cavity is connected with the gas gate arranged on the end face of the cylindrical interlayer cavity, the liquid nitrogen cavity is respectively connected with the detachable connector and the exhaust port arranged on the end face of the cylindrical interlayer cavity, and the front-end gain amplifier is respectively connected with the coaxial cable connector and the direct-current power supply connector arranged on the end face of the cylindrical interlayer cavity.
The end face of the cylindrical interlayer cavity is provided with a tuning rod interface, the tuning rod is connected with the tuning rod interface through threads, and the tuning rod extends to the coil part, close to the pluggable coil, in the vacuum cavity.
The room temperature cavity is provided with the thermocouples, the thermocouples are arranged in the vacuum cavity and near the coil part of the pluggable coil, the thermocouples are arranged in the vacuum cavity and near the front-end gain amplifier, the end face of the cylindrical interlayer cavity is provided with thermocouple interfaces, and each thermocouple is connected with the thermocouple interface.
The cylindrical interlayer cavity is made of glass fiber reinforced plastics, and the wall of the liquid nitrogen container is made of ceramics.
Activated carbon and sodium aluminosilicate are disposed within the vacuum chamber as described above.
The side wall of the liquid nitrogen container wall in the vacuum cavity is provided with a polyimide heat insulation layer except the position corresponding to the pluggable coil.
The pluggable base is made of copper.
Compared with the prior art, the invention has the following advantages:
1. the distance between the coil part of the pluggable coil and the wall of the liquid nitrogen container is 2.5mm, which is 3.5mm better than that of the existing instrument, so that the signal-to-noise ratio of imaging can be effectively improved, and the quality of the image is improved;
2. low cost design and operation can be achieved, and compared with low temperature coil design and operation which adopts liquid helium as a refrigerant, the cost is one order of magnitude lower.
3. The device is suitable for imaging the whole body of an animal, the diameter of a room temperature cavity is 32mm, and the device can be suitable for the whole body of a mouse and the head of a rat;
4. the design is carried out in a modularized mode, so that the coil part and the front-end gain amplifier of the pluggable coil can be replaced according to the requirements under the imaging experiments of different atomic nuclei;
5. the cooling time of the coil part of the pluggable coil is less than 3 hours, and incomplete volatilization of liquid nitrogen within 5 hours of test time is guaranteed.
Drawings
FIG. 1 is a schematic cross-sectional view of the present invention;
FIG. 2 is a schematic side view of the present invention.
In the figure: 1-Dewar; 2-a pluggable coil; 3-a front-end gain amplifier; 4-the wall of the liquid nitrogen container; 5-room temperature cavity; 6-a thermocouple; 7-detachable connection port; 8-an exhaust port; 9-gas gate; 10-thermocouple interface; 11-coaxial cable interface; 12-tuning rod interface; 13-a direct current power supply interface; 14-a vacuum chamber; 15-liquid nitrogen chamber.
Detailed Description
The present invention will be described in further detail with reference to examples for the purpose of facilitating understanding and practice of the invention by those of ordinary skill in the art, and it is to be understood that the present invention has been described in the illustrative embodiments and is not to be construed as limited thereto.
Example 1
As shown in fig. 1, a low-cost modular liquid nitrogen low-temperature multi-core magnetic resonance probe adopts a modular design and comprises a dewar 1, a pluggable coil 2 and a front-end gain amplifier 3.
The Dewar 1 comprises a cylindrical interlayer cavity, a room temperature cavity 5 is formed in the center of the cylindrical interlayer cavity, the interlayer of the cylindrical interlayer cavity is divided into an inner cylindrical interlayer and an outer cylindrical interlayer through a cylindrical liquid nitrogen container wall 4, the inner cylindrical interlayer and the outer cylindrical interlayer are respectively a vacuum cavity and a liquid nitrogen cavity, and the vacuum cavity is located between the room temperature cavity 5 and the liquid nitrogen cavity. When the probe works, a liquid nitrogen cavity is filled with liquid nitrogen, the vacuum cavity is vacuumized by a vacuum pump, the wall 4 of the liquid nitrogen container in the Dewar 1 is made of ceramic materials, and the end face of the cylindrical interlayer cavity is provided with a detachable connecting port 7, an exhaust port 8, a gas gate 9, two thermocouple interfaces 10, two coaxial cable interfaces 11, two tuning rod interfaces 12 and a direct-current power supply interface 13. The direct-current power supply interface 13 adopts a two-core aerial plug, the thermocouple interface 10 adopts a two-core aerial plug, and the outer diameter of the tuning rod interface 12 is 5 mm.
The liquid nitrogen cavity is connected with the detachable connecting port 7 and can be used for being connected with a self-pressurization liquid nitrogen supply system to supply liquid nitrogen in the liquid nitrogen cavity. The liquid nitrogen chamber is also connected with an exhaust port 8 for exhausting liquid nitrogen or nitrogen volatilized by the liquid nitrogen.
The vacuum chamber is connected with an air gate 9 and can be used for connecting a vacuum pump to pump out air in the vacuum chamber and reduce heat loss caused by heat exchange between the inside and the outside.
But plug coil 2 includes coil portion and plug base, but be plug between coil portion and the plug base and be connected, but plug coil 2's plug base links to each other with liquid nitrogen container wall 4, liquid nitrogen container wall 4 cuts apart vacuum cavity and liquid nitrogen cavity, but plug coil 2 is located the vacuum cavity, but plug coil 2's plug base is glued through the low temperature and is fixed with plug base and liquid nitrogen container wall 4, the low temperature is glued to be ultra-low temperature epoxy material, but this kind of fixed mode makes the temperature of plug coil 2 fall because of better heat conduction. The distance between the coil part of the pluggable coil and the wall of the liquid nitrogen container is 2.5mm, which is 3.5mm better than that of the existing instrument, so that the signal-to-noise ratio of imaging can be effectively improved, and the quality of the image is improved.
A thermocouple is arranged outside the coil part of the pluggable coil 2 and is connected with a thermocouple interface 10, so that the temperature of the coil part of the pluggable coil 2 is monitored through the thermocouple;
the coil part of the pluggable coil 2 is connected with a coaxial cable interface 11 through a front-end gain amplifier 3, and the coaxial cable interface 11 outputs the acquired magnetic resonance signal;
the tuning rod is connected with the tuning rod interface 12 through threads, extends to the coil part close to the pluggable coil 2 in the vacuum cavity and is used for tuning the vibration frequency and tuning matching;
the front-end gain amplifier 3 is connected with a direct-current power supply interface 13, and a power supply supplies power to the front-end gain amplifier 3 through the direct-current power supply interface 13;
the Dewar 1 is in a cylindrical design, the low-temperature Dewar 1 comprises a room temperature cavity 5 and a cylindrical interlayer cavity sleeved outside the room temperature cavity 5, the cylindrical interlayer cavity is divided into a vacuum cavity and a liquid nitrogen cavity through a cylindrical liquid nitrogen container wall 4, the cylindrical interlayer cavity is made of fiber reinforced plastics (glass fiber reinforced plastics), the liquid nitrogen container wall 4 is made of ceramic materials, the vacuum cavity is located between the room temperature cavity 5 and the liquid nitrogen cavity, the liquid nitrogen cavity is used for storing liquid nitrogen and preventing the liquid nitrogen from volatilizing, the vacuum cavity is used for isolating heat exchange between the inside and the outside, and a pluggable coil 2 and a front-end gain amplifier 3 are placed in the vacuum cavity; the material of the Dewar 1 is fiber reinforced plastic (glass fiber reinforced plastics).
But plug coil 2 for launching radio frequency pulse and receiving magnetic resonance signal, adopt the modularized design, including coil portion and plug base, but be connect for plug between coil portion and the plug base, be convenient for change coil portion according to the requirement of different experiments.
The front-end gain amplifier 3 is used for adjusting the receiving gain of the magnetic resonance radio-frequency signal received by the coil part of the pluggable coil 2, outputting the magnetic resonance radio-frequency signal after the receiving gain is adjusted to the cabinet through the coaxial cable interface 11 for further processing, and finally storing the magnetic resonance radio-frequency signal in a computer; and the front-end gain amplifier 3 is arranged in the vacuum cavity and is connected to the wall 4 of the liquid nitrogen container through low-temperature glue.
Liquid nitrogen container wall 4, adopt ceramic material, the cost is lower relatively, and have good heat conductivity near the liquid nitrogen temperature, but connect the plug base and the front end gain amplifier 3 of plug coil 2 on the liquid nitrogen container wall 4, liquid nitrogen container wall 4 cuts apart vacuum cavity and liquid nitrogen cavity, but plug base and front end gain amplifier 3 that glue with plug coil 2 through the low temperature all are fixed with liquid nitrogen container wall 4, but this kind of fixed mode makes plug coil 2 and front end gain amplifier 3's temperature drop because of better heat conduction effect. The pluggable coil 2 and the front-end gain amplifier 3 reach the ideal temperature.
The room temperature cavity 5 is used for placing samples, has the diameter of 32mm, can also be suitable for experiments on the whole body of a mouse and the head of a rat, and can keep the vital signs of experimental small animals;
the detachable connector 7 is used for connecting the liquid nitrogen cavity with the self-pressurization liquid nitrogen supply system and supplementing liquid nitrogen reduced due to volatilization, so that the temperature of the probe in the experimental time is ensured;
the exhaust port 8 is used for exhausting nitrogen volatilized in the liquid nitrogen cavity and ensuring the air pressure and the space of the liquid nitrogen cavity, so that new liquid nitrogen can be supplemented more easily;
a gas gate 9 connected to a vacuum pump for pumping air out of the vacuum chamber to a pressure of about 10-5pa, thereby reducing heat loss due to heat exchange between the inside and the outside;
a thermocouple interface 10, which adopts a two-core aviation plug and is used for connecting a thermocouple; the thermocouple positioned at the room temperature cavity 5 is used for monitoring the temperature at the room temperature cavity 5 and ensuring that the temperature is always at the temperature suitable for the survival of the small animals; the thermocouple positioned near the coil part of the pluggable coil 2 is used for monitoring the temperature near the coil part of the pluggable coil 2 and ensuring that the coil part is always in a low-temperature state; and the thermocouple positioned near the front-end gain amplifier 3 is used for monitoring the temperature of the front-end gain amplifier 3 and ensuring that the front-end gain amplifier 3 is always in a low-temperature state. The thermocouple interface 10 is located on the end cap of the cylindrical sandwich chamber.
A coaxial cable interface 11 for connection of a coaxial cable; the front-end gain amplifier 3 is connected with an external cabinet through a coaxial cable interface 11, and is used for transmitting the magnetic resonance signal and receiving an externally input coil excitation signal.
The tuning rod interface 12 is 5mm in outer diameter, the tuning rod is connected with the tuning rod interface 12 through threads, and the tuning rod extends to a coil part close to the pluggable coil 2 in the vacuum cavity and is used for tuning the vibration frequency and tuning matching.
The direct current power supply interface 13 adopts a two-core aviation plug for connecting a power supply and providing the power supply for the front-end gain amplifier 3, and is positioned on the end cover of the cylindrical interlayer cavity.
The principle schematic diagram of the invention is shown in fig. 1 and fig. 2, the room temperature cavity 5 and the cylindrical interlayer cavity of the Dewar 1 are mainly made of glass fiber reinforced plastics, also called glass fiber reinforced plastics, and have no interference to radio frequency signals. The dewar is mainly composed of two parts: one part is a room temperature cavity, and the other part is a cylindrical interlayer cavity positioned outside the room temperature cavity, and a sample or a small animal can be placed in the room temperature cavity. The liquid nitrogen chamber and the self-pressurizing liquid nitrogen supply system are connected through a detachable connecting port, liquid nitrogen is allowed to flow to the liquid nitrogen chamber from the self-pressurizing liquid nitrogen supply system and is filled, and the geometric volume of the liquid nitrogen chamber is about 8L. In addition, a bag of activated carbon and a bag of sodium aluminosilicate (about 100 ml) are placed in the vacuum chamber in good thermal contact with the wall 4 of the liquid nitrogen container, and these activated carbon and sodium aluminosilicate as molecular sieves are able to absorb small molecules that enter the vacuum chamber during cooling or during venting, thus prolonging the vacuum retention time of the vacuum chamber and thus ensuring the thermal insulation effect. Except for the vacuum cavity for heat insulation, other heat insulation layers are installed to reduce radiation heat loss to the maximum extent, polyimide heat insulation layers are arranged on the side wall, located in the vacuum cavity, of the liquid nitrogen container wall 4 except for the position corresponding to the pluggable coil 2 to insulate heat, eddy current is avoided, and the pluggable coil 2 is not interfered to receive magnetic resonance radio-frequency signals.
The liquid nitrogen chamber and the vacuum chamber are separated by a liquid nitrogen container wall 4, and ceramic (with the purity of 99.6%) is selected as the material of the liquid nitrogen container wall 4 on one hand because the cost is relatively low, and on the other hand, because the ceramic has good thermal conductivity near the temperature of the liquid nitrogen, and the optimal temperature is about 80K to 90K; the length of the liquid nitrogen container wall 4 is 100mm, other devices are convenient to install in the later period, the pluggable base of the pluggable coil 2 and the front-end gain amplifier 3 are connected to the liquid nitrogen container wall 4, and the pluggable coil 2 and the front-end gain amplifier 3 reach ideal temperatures. A temperature gradient exists between the liquid nitrogen cavity and the room temperature cavity 5, the liquid nitrogen cavity is partially low-temperature transmitted through the wall 4 of the liquid nitrogen container to ensure the normal work of the coil part of the pluggable coil 2 and the front-end gain amplifier 3, the room temperature cavity 5 is kept at room temperature to ensure the activity of a sample or a small animal, and in this case, the room temperature is kept at the position of the animal by a hot air flow introducing method.
The low temperature dewar cooling process is completed using the following steps:
1. low temperature dewar vacuum accumulation: evacuating the vacuum chamber to below 10 deg.C by vacuum pump-5Pressure of Pa.
2. Starting a cooling process: 8L of liquid nitrogen is injected into the liquid nitrogen cavity through the self-pressurization liquid nitrogen supply system.
3. And (3) cooling transition period: after 45 minutes, the vacuum chamber can be disconnected from the vacuum pump.
4. The temperature of the pluggable coil is stable.
The pluggable base of the pluggable coil 2 is made of flat (1.2 mm thick) copper to increase the contact area with the liquid nitrogen container wall 4 to the maximum extent, and the pluggable base of the pluggable coil 2 is connected with the liquid nitrogen container wall 4 using low-temperature glue, thereby increasing the heat transfer therebetween. The front-end gain amplifier 3 is connected to the liquid nitrogen container wall 4 by a low temperature glue, and the liquid nitrogen container wall 4 is in direct contact with liquid nitrogen, thereby ensuring heat transfer therebetween.
The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.
Claims (9)
1. A low-cost modularized liquid nitrogen low-temperature multi-core magnetic resonance probe comprises a Dewar (1) and is characterized by further comprising a pluggable coil (2) and a front-end gain amplifier (3), wherein the Dewar (1) comprises a cylindrical interlayer cavity, a room temperature cavity (5) is formed in the center of the cylindrical interlayer cavity, the interlayer of the cylindrical interlayer cavity is divided into a vacuum cavity and a liquid nitrogen cavity through a liquid nitrogen container wall (4), the vacuum cavity is located between the room temperature cavity (5) and the liquid nitrogen cavity,
the pluggable coil (2) and the front-end gain amplifier (3) are arranged in the vacuum cavity, the pluggable coil (2) comprises a coil part and a pluggable base, the coil part and the pluggable base are connected in a pluggable mode, and the pluggable coil (2) is connected with the front-end gain amplifier (3).
2. A low cost modular liquid nitrogen cryogenic multi-nuclear magnetic resonance probe according to claim 1, wherein the pluggable base of the coil (2) and the front end gain amplifier (3) are connected to the liquid nitrogen container wall (4) by cryogenic glue.
3. The low-cost modular liquid nitrogen low-temperature multi-core magnetic resonance probe according to claim 1, wherein the vacuum chamber is connected with a gas gate (9) arranged on the end face of the cylindrical interlayer chamber, the liquid nitrogen chamber is respectively connected with a detachable connector (7) and an exhaust port (8) arranged on the end face of the cylindrical interlayer chamber, and the front-end gain amplifier (3) is respectively connected with a coaxial cable interface (11) and a direct-current power supply interface (13) arranged on the end face of the cylindrical interlayer chamber.
4. The low-cost modular liquid nitrogen low-temperature multi-core magnetic resonance probe as claimed in claim 1, wherein a tuning rod interface (12) is arranged on the end face of the cylindrical interlayer cavity, the tuning rod is connected with the tuning rod interface (12) through threads, and the tuning rod extends to a coil part close to the pluggable coil (2) in the vacuum cavity.
5. The low-cost modular liquid nitrogen low-temperature multi-core magnetic resonance probe as claimed in claim 1, wherein a thermocouple is arranged in the room temperature cavity (5), a thermocouple is arranged in the vacuum cavity near the coil part of the pluggable coil (2), a thermocouple is arranged in the vacuum cavity near the front-end gain amplifier (3), a thermocouple interface (10) is arranged on the end face of the cylindrical interlayer cavity, and each thermocouple is connected with the thermocouple interface (10).
6. The low-cost modular liquid nitrogen low-temperature multi-core magnetic resonance probe according to claim 1, wherein the cylindrical sandwich cavity is made of glass fiber reinforced plastic, and the wall (4) of the liquid nitrogen container is made of ceramic.
7. The low-cost modular liquid nitrogen cryogenic multi-core magnetic resonance probe according to claim 1, wherein activated carbon and sodium aluminosilicate are disposed in the vacuum chamber.
8. The low-cost modular liquid nitrogen low-temperature multi-core magnetic resonance probe according to claim 1, wherein the side wall of the liquid nitrogen container wall (4) in the vacuum chamber is provided with a polyimide heat insulation layer except the position corresponding to the pluggable coil (2).
9. The low-cost modular liquid nitrogen cryogenic multinuclear magnetic resonance probe of claim 2, wherein the pluggable mount is copper.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111319366.1A CN114114108B (en) | 2021-11-09 | 2021-11-09 | Low-cost modular liquid nitrogen low-temperature multi-core magnetic resonance probe |
| US18/284,549 US11959982B2 (en) | 2021-11-09 | 2021-11-10 | Low-cost modular liquid nitrogen low-temperature multi-nuclear magnetic resonance probe |
| PCT/CN2021/129680 WO2023082073A1 (en) | 2021-11-09 | 2021-11-10 | Low-cost modular cryogenic liquid nitrogen multi-nuclear magnetic resonance probe |
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| CN202111319366.1A CN114114108B (en) | 2021-11-09 | 2021-11-09 | Low-cost modular liquid nitrogen low-temperature multi-core magnetic resonance probe |
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| CN114114108A true CN114114108A (en) | 2022-03-01 |
| CN114114108B CN114114108B (en) | 2023-01-24 |
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| US (1) | US11959982B2 (en) |
| CN (1) | CN114114108B (en) |
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| KR101992478B1 (en) * | 2019-04-26 | 2019-06-24 | 서울대학교산학협력단 | Probe system for low-temperature high precision heat transport measurement and apparatus including the same |
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| US11959982B2 (en) | 2024-04-16 |
| US20240085502A1 (en) | 2024-03-14 |
| CN114114108B (en) | 2023-01-24 |
| WO2023082073A1 (en) | 2023-05-19 |
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